Public transport should only be used for essential/work journeys not leisure journeys.
Is that in the (English) regulations (see below) or is it just your opinion? I suspect the latter.
The Health Protection (Coronavirus, Restrictions) (England) Regulations 2020
These Regulations require the closure of businesses selling food or drink for consumption on the premises, and businesses listed in Part 2 of Schedule 2, to protect against the risks to public health arising from coronavirus, except for limited permitted uses. Restrictions are imposed on...
www.legislation.gov.uk